." >> catherine: nasa now thinks that mars was once capable of supporting very simple forms of life. the discovery was made by the mars rover, which arrived on the red planet back in august. kron 4's charles clifford has more. >> reporter: for the past few months the curiosity rover has been exploring an area just north of the martian equator...here...near what's called the gale crater. at the moment the probe is sitting in what's believed to be an ancient stream bed. using a variety of scientific instruments, the probe has been drilling into and analyzing rocks.. looking for signs of life. what it's found in this dust is sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon... the basic chemical building blocks of life as we know it. they've also found mineral clay, basically dried out mud, which indicates that at some point in the distant pst, probably millions of years ago, this area was covered in fresh water. the water was fresh, not to salty or acidic.. that means that microbial life could have survived here. there are also traces of sulfates and sulfides... a possible food